The term "planar display" as used herein means those adapted to display an image by using a liquid crystal, plasma display tubes, light emitting diodes, electroluminescence or the like. Planar displays are used as thin television sets and various displays.
A glass plate, ceramic plate, porcelain-enameled steel plate or the like is used as a substrate. In order to form a semiconductor in the form of a thin film on the substrate so as to fabricate a thin-film semiconductor substrate suitable for use in driving a planar display, a variety of treatments such as various chemical treatments, masking, etching and washing are carried out. As materials of substrate-holding containers employed in such treatments, glass fiber containing polyphenylene sulfide resins (hereinafter abbreviated as "GF-containing PPS resins") and fluorine plastics such as perfluoroalkoxy-substituted polytetrafluoroethylene resin (hereinafter abbreviated as "PFA resin") have heretofore been used.
Liquid-crystal displays, one type of planar displays, are generally composed of two glass substrates, each of which is equipped with a transparent electrode attached thereon, and a liquid crystal layer having a thickness of several micrometers and interposed between the glass substrates. In order to form the transparent electrode on each of the glass substrate, treatments such as washing, masking and etching are conducted. The above-mentioned holding containers have also been used as glass substrate holding containers in such treatments.
A holding container made of a GF-containing PPS resin is however accompanied by drawbacks that the glass fibers in the resin are dissolved by an etching treatment, the resin and glass fiber are caused to separate as fine powder from the surface of the holding container and the fine powder deposits on the surface of the substrate to result in contamination of the substrate surface. Moreover, a holding container made of a fluorine plastic is accompanied by drawbacks that it is prone to a deformation due to its low stiffness, thereby involving a potential problem of accidental drop of substrates in the course of their treatments, and it cannot be used in any step involving heating due to its softening and deformation at elevated temperatures.